Dealing not only with the myriad of modern, printed, theological books, but with those antiquarian & rare, we get to see all sorts of odds and ends that leave us perpetually fascinated (though perhaps to others we appear simply bizarre).
Here's a recent fun blippet of bookishness. Observe a lovely 14th-15th century antiphonal manuscript leaf written on vellum:
Domine quinque talenta tradidisti michi ecce alia quinque super lucratus [the next word on the next page would have been sum].
Lord, you had given me five talents, and behold I have made five more.
If I am not mistaken, this would have been sung, for instance, as the communion antiphon for the feast of a confessor.
But here's the interesting part. Note the spelling: michi. That's mihi (to me) with an added, hard c so it would be pronounced miki. Supposedly mihi was pronouned like that in at least some medieval Latin. But have you ever had your choir or schola master tell you, when singing in Latin, that you are NOT to aspirate those h's, but rather to pronounce them like a k? (Since h is not voiced, the choir's sound would momentarily drop out as everyone aspirates.) I suspect that here, on this manuscript, it is written that way precisely because it was meant to be sung that way - and not simply because that is how it was pronounced generally. Yes, this is something of a guess on my part. But judging from the lot of Latin I've seen in books and other manuscripts, it is not all that common to see michi.
If you, dear reader, know any better, I am docile.